0 A.D. is a free, open-source, cross-platform real-time strategy (RTS) game of ancient warfare. It's a historically-based war/economy game that allows players to relive or rewrite the history of twelve ancient civilizations, from Iberia to Mauryan India, each depicted at their peak of economic growth and military prowess. Developed using Pyrogenesis, a ground-breaking new game engine custom-built to suit this project, 0 A.D. will give players a rich and entertaining real-time gaming experience.

Whatever you do, don't turn this into one of those fast-paced, unitspamming kinda rts games. I'd give my right testicle for a tactical rts game. If you ever played the game Alexander, you should know what i mean.